This question asks about Newton's universal law of gravitation. To answer it, we need to recall the mathematical formulation of this law and understand the relationships between gravitational force, masses of the bodies, and the distance between them.
A) Directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres
This statement perfectly matches the mathematical formulation and the definition of Newton's universal law of gravitation. As derived from the formula \(F = G \frac{m_1 m_2}{r^2}\), the force \(F\) is directly proportional to \(m_1 m_2\) and inversely proportional to \(r^2\).
The question asks about the first experimental measurement of the universal gravitational constant 'G'. This requires recalling the history of gravitational studies and the scientists associated with key discoveries and measurements.
D) Henry Cavendish — Henry Cavendish conducted the first experiment to measure the universal gravitational constant 'G' in 1798 using a torsion balance. His experiment provided the first accurate value for G, which was crucial for calculating the mass and density of the Earth.
The question asks for the approximate value of the universal gravitational constant (G). This is a fundamental physical constant whose value is determined experimentally. We need to recall its standard accepted value and units.
C) \(6.674 \times 10^{-11} \ N \ m^2/kg^2\) is the internationally accepted and most commonly used approximate value for the universal gravitational constant (G).
The question asks for the best classification of gravitational force. We need to recall the fundamental properties of gravity as described by Newton's Law of Universal Gravitation and distinguish it from other types of forces.
C) Non-contact (action-at-a-distance) force that acts between any two masses in the universe. This accurately describes gravitational force. It does not require physical contact (e.g., the Earth pulls the Moon without touching it), and it acts universally between any objects possessing mass.
The question asks to identify which of Kepler's laws describes the elliptical nature of planetary orbits and the Sun's position at one focus. We need to recall the definitions of Kepler's three laws of planetary motion and Newton's laws to determine the correct option.
Correct Option: C) Kepler's first law (the Law of Orbits) states that every planet revolves around the Sun in an elliptical orbit, with the Sun located at one focus. This is the fundamental law describing the geometry of planetary paths.
The question asks about Kepler's second law, also known as the Law of Areas. This law describes the motion of planets around the Sun.
Based on the definition of Kepler's second law, the correct option is the one that describes equal areas being swept out in equal time intervals.
Correct Option: A) Equal areas in equal intervals of time